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Grape pomace

Datasheet

Description
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Common names 

Grape, common grapevine, European grape, grapevine [English]; raisin, vigne [French]; uva, vite comune, vite euroasiatica [Italian]; uva, vid, parra [Spanish]; druil, wijnstok [Dutch]; weintraube, weinrebe, rebe, echter weinstock [German]; uva, videira [Portuguese]; Грозде [Bulgarian]; Grožđe [Croatian]; Σταφύλι [Greek]; szőlő, szőlőfélék [Hungarian]; Winogrono, Winorośl [Polish]; Виногра́д [Russian]; Грожђе [Serbian]; Üzüm [Turkish]; druiwe [Afrikaaner]; zabibu, mizabibu [kiswahili]; anggur, buah anggur [bahasa Indonesian]; anggur [Malaysian]; ubas [Philippines].; الكرمة ;عنب [Arabic]; আঙ্গুর [Bengali]; 葡萄, 葡萄属 [Chinese]; દ્રાક્ષ [Gujarati]; انگور [Persian]; ענב ,גפן היין [Hebrew]; अंगूर [Hindi]; ブドウ, ブドウ属[Japanese]; ದ್ರಾಕ್ಷಿ [Kannada]; 포도, 포도속 [Korean]; മുന്തിരിങ്ങ [Malalayam]; द्राक्ष [Marathi]; अङ्गूर [Nepali]; ਅੰਗੂਰ [Punjabi]; திராட்சைப்பழம் [Tamil]; ద్రాక్ష [Telugu]; nho, cây nho, chi nho [Vietnamese]

Products: grape pomace, grape marc, grape pulp [English]; marc de raisin, marc de raisin eraflé, marc de raisin degrappé, marc de raisin épuisé, pulpe de raisin [French]; orujo de uva, orujo de vino [Spanish]; vinaccia [Italian]

Synonyms 

Vitis sylvestris C. C. Gmel.

Description 

Grapevine (Vitis vinifera L.) is a woody vine cultivated worldwide for its edible berries (grapes) that are eaten fresh or pressed to make beverages. Most of grape juice is fermented and macerated to make wine, and the rest is used as a refreshing beverage. Grape processing generates massive amounts of by-products that can be broadly classified as follows: solid by-products (leaves, stems, seeds, skins and pulp), highly viscous by-products (lees), and low-viscosity by-products (wastewater) (Bekhit et al., 2016). The seeds (pips) are sometimes extracted to make oil. This datasheet deals with grape pomace (grape marc), which is the main solid residue of grape processing. Grape pomace includes at least the pressed skins and the disrupted cells of grape pulp, and, depending on the process, the stems and the seeds. Grape leaves and grape seeds and oil meal are presented in their own datasheets.

Categorization

The categorisation of grape pomaces is difficult. Moreso than other food industries, wine-making practices are incredibly diverse, and, while rooted in tradition, they have been embracing changes required both by the globalised consumer demand and by the legislative pressure to reduce their environmental footprint. The standard vinification process consists of de-stemming, crushing, storage, screening, fermentation, maturation, stabilization, and bottling. However, wine producers use different process routes that have significant impacts both on wine quality and on the nature of the by-products (Letaief, 2016). As a result, the physical and chemical composition of wine and grape juice by-products depend on many factors: purpose of the crop (white wine, red wine, spirits, juice...), grape variety, grape maturity, and the wide range of techniques and machinery used for grape separation, crushing, fermentation, maceration and distillery (Ye ZhiJing et al., 2016). Indeed, the nature and nutritional value of those products should be ideally determined on a case-by-case basis, a situation that has been remarked upon from the 1890s to the 2010s (Cornevin, 1892; Bekhit et al., 2016). 

The terminology of winery by-products can be confusing. Grape pomace and grape marc are sometimes considered to be distinct products: in that case, the marc only contains the skins and the pulp (Göhl, 1982; El Boushy et al., 2000). Most of the time, however, pomace and marc are used either interchangeably as synonyms, or exclusively. The European Union, for instance, defines grape marc as "the residue from the pressing of fresh grapes, whether or not fermented" (European Council Regulation (EC) 479/2008). Some producers of grape by-products for animal feeds use the term "grape pulp" for the by-product without stems and seeds (Désialis, 2016), but other producers do no make a difference between pomace and pulp. Grape pulp can also be a food product composed of actual pulp (without the skins). Many scientific papers discussing the feeding value of grape pomace do not mention the physical composition of the product or its status regarding destemming or distillation, and call it pomace, marc, pulp, winery by-product etc. This datasheet will use the terms pomace and marc as synonyms.

Grape pomace includes the skins and the pulp, usually the seeds and, in some cases, the stems. Leaving the stems with the grapes during the crushing, pressing, and even during fermentation used to be the traditional practice (Cornevin, 1892). The tannin-rich stems gives the wine a more bitter, astringent and herbaceous taste. However, as this type of wine has become less popular, current wine-making practices favour destemming and many wines are made with grapes crushed after the removal of the stems. Leaving the stems is still required for certain red wines when the organoleptic properties provided by the stems are desirable. Some white wines do not require destemming, as the stems do not come in contact with the juice during the process. Destemming can also be partial in order to control precisely the organoleptic effect of the stems (Ye ZhiJing et al., 2016; Letaief, 2016). It should be noted that in some cases the destemming operation is done after the recovery of the pomace (Magnier, 1991). Grape pomace made of non-destemmed berries is composed of about 30% stems, 30% seeds and 40% skins and pulp, while grape pomace made from destemmed berries consists of about 40% seeds and 60% skin and pulp (Göhl, 1982). Wet grape pomace represents between 25 and 45% of the fresh berry (15% for dried pomace) (Wadhwa et al., 2013), but other authors provide a value of 20% (Bekhit et al., 2016). 

Grape pomace is often processed to extract the residual ethanol for the production of liquors, resulting in "exhausted" pomace. In the European Union, wine producers can be required to send winery by-products to distilleries for ethanol extraction: because overpressing is prohibited to maintain wine quality, grape marcs must contain a minimum quantity of alcohol (Ye ZhiJing et al., 2016; See also EC Regulation 479/2008 above). It therefore probable that grape pomaces available in the EU are from distilleries and have a lower content in ethanol than pomaces obtained from wineries.

Grape pomace, exhausted or not, can be further processed to remove the seeds (for grape seed oil extraction). The resulting product, that should only contain the pulp and the skins, is sometimes called grape pulp or even grape marc, as noted above. Because of its lower fibre content, this product has a better value for livestock than other pomaces.

Uses

Due to its high content of fibre (and particularly lignin) and the presence of phenolic compounds, grape pomace is poorly digestible. It can be used to feed ruminants, horses and rabbits, in association with feeds having a better nutritive value, but it is not recommended for pigs and poultry, at least not as a source of energy and protein. Grape pomace can be fed fresh, but, as it is highly perishable and produced seasonally, it must be dried or ensiled for longer preservation (NRC, 1983; Demarquilly et al., 2009). Other uses include fertilizers and composts. In the past decades, grape pomace and other grape by-products have been recognized as potential sources of valuable bioactive compounds, notably antioxidants. Grape pomace is already used industrially for the extraction of anthocyanins (Ye ZhiJing et al., 2016; Letaief, 2016). Indeed, since the mid-2000s, the scientific literature about the feed utilisation of grape pomace has been largely dedicated to investigating grape pomace as a source of beneficial polyphenols and antioxidants, notably for ruminants and poultry.

Distribution 

Grapevine is native from a region comprising northeastern Afghanistan to the southern borders of the Black sea and Caspian Sea. It was domesticated there around 4000 BCE and later spread to the Mediterranean Basin, Western Europe, India, China and Japan. Grapevine was introduced in the Americas by the Spaniards. Grapevine is now cultivated worldwide. In some cases, it hybridized with native Vitis species, resulting in cultivars adapted to local conditions. Grapevine is grown in both hemispheres, predominantly within 20 and 50° N and within 20 and 40°S. Grapevine can grow in tropical areas at altitudes between 300 and 2000 m. However, growth and fruit production are poorer above 1200 m. Grapevine requires a long, sunny, and warm season for the grapes to ripen, and a relatively severe winter that promotes plant dormancy. Grapevine withstands winter frost down to -20°C but light frost of -3 to -5°C kills regrowth during spring and hampers harvest. Temperatures of 25-30°C are optimal for shoot and berry summer growth. Hot and dry summer is best suited for fruit production as it prevents diseases. Grapevine grows on most soils, light or heavy, deep or shallow, fertile or not, but responds to better soils with higher yields. Soil pH should be between 5 and 8; values slightly below 7 are considered best. Light soils promote early ripening and a high sugar content. Soil texture is more important than soil fertility: deep and well-drained soils are preferred as they favour extensive root development. Grapevine is tolerant of drought stress and still survives and grows in semi-arid places where other crops fail. Grapevine is a full sunlight species, but it is necessary that its leaves protect the fruits from sun scorch. Grapevine should be sheltered or planted where strong winds do not occur (Ecocrop, 2016; Ketsa et al., 1991).

Production

Grape is one of the world's most important fruit crop in area, production and value. In 2012, grapes were cultivated on more than 7 million ha that produced 69 million t of fruits with an average yield of 9.6 t/ha. 40 million t of grapes were used for wine (about 90%) and juice (fresh or concentrated) production, 24 for fresh fruit and 5 for dried grapes (raisin) (OIV, 2016; Castellucci et al., 2013). The most important producers were China (9.6 million t), USA (6.6 million t), Italy (5.8 million t), France (5.3 million t), Spain (5.2 million t), Turkey (4.2 million t), Chile (3.2 million t), Argentina (2.8 million t) and Iran (2.1 million t). The EU represents 75% of grape production and 57% of wine production. The main wine producers are Italy, France, Spain (where most of grape production is used for wine) and the USA. China is mostly a producer of fresh fruit (FAO, 2016).

For 2012, assuming that 40 million t of fresh grapes are processed into wine and juice, and a residue-to-product ratio of 0.15 for dried pomace (Wadhwa et al., 2013), the amount of dried pomace worldwide can be estimated at 6 million t. This value is almost twice the value of 3.4 million t provided by FAO, 2016 but remains of the same order of magnitude.

Processes 

Drying

Grape pomace is a fresh (up to 65-68% water) and perishable product, and it must be dried if it cannot be fed immediately or ensiled (Février et al., 2009). Grape pomace is usually dried in large rotary drum driers. Pomace is introduced at the top where burners blow a flame drier by means of a large fan. The blown hot air mixes with the pomace and carries gases and moisture vapour out of the drum drier. The wet pomace drops into the hot air combustion gases zone at the furnace end of the drier. The dried pomace is then hammer-milled into a fine mash, which may be mixed with small amounts of molasses to improve its energy content and its palatability. Addition of lime can be used to bind the pectines and raise the pH (El Boushy et al., 2000). In a process described in Australia, drying occurs continuously for approximately 20 min, in a gas-fired rotary drum heated to approximately 120°C. The resulting dry meal is ground and then steam-pelleted at 85°C (Moate et al., 2014).

Ensiling

Ensiling has been used in Western Europe since the 19th century as an efficient method to preserve grape pomace for winter feeding of livestock (Cornevin, 1892). In the Mediterranean area, ensiled grape pomace has been commonly used by sheep farmers as a backup feed or emergency feed (Reyne et al., 1977). Winery pomace can be stored for a time by heaping and pressing, but dust formation may become a problem owing to disintegration of the pulp (Göhl, 1982). Because winery pomace is already acid, it can be relatively easy to ensile (Göhl, 1982) and good silage has been made by storing pomace in sealed polyethylene bags (Alipour et al., 2007). However, the presence of water soluble carbohydrates and ethanol may create conditions that do not promote lactic acid fermentation, and it may be necessary to use chemical additives (e.g. formic acid, acidic acid, or sulfuric acid) or lactic acid bacteria inoculants (Zheng Yi et al., 2012). Early feed practitioners recommended to press the pomace and to cover it as hermetically as possible. Adding grape leaves and fine straw was a common practice (Cornevin, 1892). In warm-climate countries, ensiling fresh grape marc with high-quality by-products, such as wheat bran or tomato pulp, was found to improve storage quality and give a well-preserved palatable feedstuff (Chedly et al., 1999).

Ensiling has been shown to reduce the content in phenolics, condensed tannins, free tannins (but not bound tannins) and saponins, thus improving the feeding value of grape pomace (Winkler et al., 2015; Spanghero et al., 2009; Alipour et al., 2007). However, this means that ensiling is not recommended when grape pomace is included at low levels in order to induce health-promoting effects (Winkler et al., 2015).

Treatment with polyethylene glycol (PEG)

An early trial in Algeria found that treatment of grape pomace with PEG was efficient to inactivate tannins and to increase the in vivo digestibility of OM and protein in sheep. However, such treatment was not economical at the time (Larwence et al., 1984). Later trials in Iran and Spain have confirmed these findings. Treatment with PEG was shown to improve the digestibility (gas method) of grape pomace by inactivating tannins (Alipour et al., 2007). In another study PEG treatment improved in vitro protein digestibility but not in vitro DM digestibility (Molina-Alcaide et al., 2008).

Alkali treatments

Treatment with NaOH has been shown to improve significantly the digestibility of grape pomace, probably by increasing the availability of nitrogen and inactivating tannins, but a too strong NaOH treatment may also inhibit microbial activity (Larwence et al., 1983b; Larwence et al., 1985). Treatment with ammonia decreased tannin content but did not improve digestibility (Magnier, 1991). Treatment of grape pomace silage with urea (up to 2% DM) was ineffective to improve the nutritive value of the silage (Eraso Luca de Tena et al., 1992).

Environmental impact 

Grape pomace and other grape processing residues, when released in the environment, can lead to serious pollution, ranging from surface and groundwater pollution to foul odors. They also attract flies and pests. The use of these products for fertilizers or composts can cause the increase of nitrogen leaching in soils and oxygen depletion due to the presence of tannins and other compounds (Bekhit et al., 2016). Disposing of pomace as fertilizer back into the vineyards may cause phytopathological issues (Baumgärtel et al., 2007), These products also contain heavy metals. A better environmental management of these wastes and their utilization for other purposes, including livestock feeding, is increasingly necessary, and there is a strong legislative pressure in that direction (Bekhit et al., 2016). It is possible that grape pomace is still underused in animal feeding: in the late 1980s, it was estimated that only 3% of grape pomace produced in the Mediterranean area were fed to livestock (Magnier, 1991).

Nutritional aspects
Nutritional attributes 

Grape pomace is a highly variable product. Not only it contains variable proportions of pulp, stems, seeds and skins, but grape cultivars, fruit maturity, and the production process (winery, distillery, juice) all have effects on its composition. However, in spite of this variability, grape pomace is a feed of moderate to low nutritional value. Its protein content is about 14% DM (11-16%) and its fibre content is generally high (ADF 55% DM ranging from 43 to 66%) with exceptional levels of lignin (33% DM, from 19 to 46%). Pomace containing only skins and pulp has a lower lignin content (17-26% DM, Bekhit et al., 2016), though still much higher than that of most feeds. Grape pomace contains 4-8% DM of lipids, due to the presence of oil-rich seeds. Other components are also variable and depend, for instance, on cultivars and processes: pomace from red wine production contains residual yeast biomass and ethanol in addition to fermented grape material, whereas pomace from white wine production contains higher levels of water-soluble carbohydrates and less ethanol (Zheng Yi et al., 2012). Sugar content, for instance, can vary from 4-9% (red wine pomace) to 28-31% (white wine pomace) (Baumgärtel et al., 2007; Winkler et al., 2015).

Potential constraints 

Tannins

Grape berries and their by-products, particularly the seeds and the skins, contain important though variable amounts of phenolic compounds (Chedea et al., 2016), and particularly flavonoids, which include anthocyanins, flavonols, and flavan-3-ols (catechin, epicatechin). Condensed tannins (proanthocyanidins) are polymers of flavan-3-ols of different molecular weights (Ye ZhiJing et al., 2016). Grape pomace can contain as much as 20% condensed tannins (Molina-Alcaide et al., 2008). These compounds form complexes with proteins in the feed and with digestive enzymes leading to disruption of the digestion process and to loss of nutrients. They also interfere with mineral absorption, causing damage to the mucosal lining of the gastrointestinal tract (Bekhit et al., 2016). Vinification methods influence the tannin content of grape pomace: particularly, higher fermentation temperatures and extended maceration time increase the release of phenolic compounds in the wine, and reduce their amount in the by-products (Ye ZhiJing et al., 2016). The high tannin content of grape pomaces is, along with fibre, one of the main contributor to their low digestibility and to their generally low nutritive value.

Flavonoids are recognized as antioxidants with positive effects on the prevention of oxidative damage in tissues by the reduction of lipidic oxidation and/or blocking the production of free radicals (Letaief, 2016). For that reason, the inclusion of small amounts of grape pomace in the diets of ruminants, but also of poultry and pigs, is being investigated for its potential beneficial effects both on animal health and on the quality of animal products. The effect of grape pomace tannins on the reduction of methane emissions by ruminants is also being studied (Moate et al., 2014).

Copper toxicity

There have been reports in Brazil of lethal intoxication of sheep fed grape pomace derived from grapevine treated with copper-based fungicides (Reis et al., 2015).

Pesticides residues

Grapevine is treated with a variety of pesticides. In Australia, an assessment of animal products derived from livestock fed grape pomace treated with registered pesticides found that the risk of residues was low for the majority of chemicals (MacLachlan, 2010).

Spoilage

Fresh grape pomace spoils more or less readily. Depending on the conditions and on the nature of the product, it can remain edible for a week (Février et al., 2009) or can become inedible in less than 24 hours (Hentges et al., 1982).

Ruminants 

Grape pomace has long been used to feed ruminants, though this use varies widely depending on the region. In the 2000s, its seasonal use was still reported in major wine growing regions such as France, Spain, Greece and the South of Australia, but it had largely regressed in Germany (Baumgärtel et al., 2007). Grape pomace is generally seen as having low to moderate nutritional value, depending on the amount of stems and seeds left in the product, and on the more or less important presence of tannins. Its feeding value has been found to be comparable to that of a hay or even a straw (Demarquilly et al., 1976; Hentges et al., 1982; Magnier, 1991; Winkler et al., 2015). Because of its low feeding value, grape pomace is more valuable for ruminants at maintenance or for low-producing animals, and should always be fed with sources of protein and energy. A 10-day transition is recommended. Grape pomace is more suitable for sheep and goats than for cattle, though it can be given to beef cows and heifers (Magnier, 1991).

Since the 2000, investigations have focused on the potential benefits of grape pomace phenols on animal health, product quality and environmental performance, such as N excretion and methane emissions.

Palatability and intake

Grape pomace has long been described as being palatable to ruminants. Sheep were observed to select the seeds and the skins and discard the stems when fed whole pomace (Cornevin, 1892). Sheep can consume 90 to 130 g DM/kg P0.75 (1.5-2,5 kg/d for a 60 kg sheep) of fresh and ensiled grape marc. Intake is lower for dried pomace and exhausted pomace. Grape pomace without seeds and stems is also palatable but intake is slighly lower (50 to 122 g DM/kg P0.75) (Magnier, 1991). Fresh grape pomace fed to grazing yearling heifers and beef cows was found very palatable. Beef cows could consume up to 13.6 kg/d of pomace in 2 hours (Hentges et al., 1982).

Digestibility and degradability

In vitro and in vivo digestibility of grape pomace is generally low to very low, and, with few exceptions, in the 25-35% range (Magnier, 1991). In vitro DM digestibility of pomace from 3 grape cultivars in cattle, sheep and goat ranged from 26 to 36%; the lowest values corresponded to the highest phenolics content (Oluyemi et al., 1982). In a comparison of 2 types of winery grape pomace, in vivo OM digestibility ranged from low (red wine, 32%) to medium (white wine, 56%): the first pomace had 31% NDF and 4% sugars while the other had 51% NDF and 27% sugars (Baumgärtel et al., 2007). However, another trial found red wine pomace to have a better OM digestibility than white wine pomace (39 vs 32%) (Winkler et al., 2015). A comparison of red and white grape juice pomaces gave higher in vivo OM digestibilities values for white grape pomace (39 vs 32%) (Zalikarenab et al., 2007). A trial in China with fistulated sheep concluded that 2.25 g/kg DM condensed tannins from grape pomace improved the apparent digestibility and retention of feed protein (Zhao Dong et al., 2014).

Ruminal degradability was also found to be low. Some authors report values in the 25-40% range for DM effective degradabilities (Molina-Alcaide et al., 2008; Abarghuei et al., 2015), while other authors report values lower than 20% (Sarcicek et al., 2002). There is a wide range of N degradability, from very low values (< 20%) reported for juice pomaces (Abarghuei et al., 2015; Sarcicek et al., 2002) to values in the 40-50% range (Molina-Alcaide et al., 2008).

Dairy cows

Grape pomace is generally not recommended for dairy cows as it tends to depress milk yield (Magnier, 1991). Early trials showed that grape pomace without stems could be fed to dairy cows in amounts up to 6.5 kg/d and was a good feed when supplemented with concentrates and legume hay, though at this level of inclusion the milk yield tends to drop and the butterfat content increases. Larger amounts caused inflammation of the mucosa in the digestive system (Göhl, 1982). In Greece, dairy cows could be fed a diet containing 20% ensiled wet grape marc without affecting DM intake, milk yield, milk composition, and body condition (Belibasakis et al., 1996). In Australia, feeding of dried grape marc (5 kg DM/d) instead of alfalfa hay to dairy cows in late lactation had no effect on milk yield or concentrations of protein and lactose in milk, but milk fat concentration and, consequently, yield of milk fat was reduced. The feeding of ensiled grape marc (5 kg DM/d) instead of alfalfa hay to dairy cows in late lactation had no effect on concentrations of milk fat, milk protein, and milk lactose, but milk yield and yields of milk fat, milk protein, and milk lactose were all reduced. The feeding of both dried and ensiled grape marc resulted in milk fat with enhanced concentrations of MUFA, PUFA, and cis-9,trans-11 linoleic acid (Moate et al., 2014).

Since the 2000s, studies have investigated the potential benefits of the flavonoids and antioxidants of grape pomace. In Denmark, dairy cows fed a high protein diet supplemented with 4.5 g/d of grape pomace did not show significant improvement in milk yield and protein yield (Nielsen et al., 2004). In Romania, dried grape pomace included at 3 to 5 kg/d had no effect on milk yield and milk composition (Nistor et al., 2014). In Germany, supplementation of dairy cows with 1% grape seed and marc meal extract (containing 5.2% polyphenols) from week 3 prepartum to week 9 increased milk production but had no significant effects on inflammation and the occurrence of endoplasmic reticulum stress in the liver of dairy cows during early lactation (Gessner et al., 2015).

Other effects of grape marc flavonoids on dairy metabolism have been researched. In New Zealand, cows receiving 3 kg DM/d of grape pomace excreted 22% more N in feces compared with the control group, had a lower plasma urea nitrogen concentration and unchanged urine urea concentration: such altered partitioning of N toward feces instead of absorption could be beneficial when feeding diets high in rumen-degradable protein (Greenwood et al., 2012). In Australia, dairy cows fed 5 kg DM/d of dried or ensiled grape pomace or ensiled grape pomace showed a 20% reduction in CH4 emissions without a concomitant reduction in DM intake. These reductions in CH4 emissions were associated with changes in the ruminal bacterial and archaeal communities (Moate et al., 2014).

Beef cattle

Most trials involving growing beef cattle show that including grape pomace above 10% is detrimental to performance. In Cyprus, inclusion of dried grape marc at 15 and 30 % of calf fattening diets tended to reduce live-weight gain at the higher level and to reduce killing-out percentage and increase feed intake at both levels, resulting in poor feed utilization (Hadjipanayiotou et al., 1976). Similar results were obtained in a trial in California, USA, where dried grape pomace mixed at 20% to replace barley in finishing steer diets had no effect on gain or carcass composition but increased intake by 15%, which was detrimental to feed efficiency (Hentges et al., 1982). In Chile, steers fed diets containing up to 15% grape marc showed decreasing liveweight grains 45 days into the trial; body weight, carcass yield, dorsal fat and loin eye area were also negatively affected (Manterola et al., 1997). Likewise, negative results on daily gain and feed efficiency were obtained with young cattle fed 15 to 22.5% grape marc (Stojanovic et al., 1989). Not all trials are negative: in Romania, replacing barley by dried grape pomace (20% dietary levels) in the diets of fattening steers did not affect performance (Voicu et al., 2014).

Grape pomace can be fed to beef cows up to 35% of the diet (Magnier, 1991).

Sheep

Growing sheep

In Cyprus, lambs fed diets containing 30% grape marc in substitution for barley made similar liveweight gains as the lambs fed the control diet but consumed more feed and feed efficiency was lower. It was recommended to use diets containing 10-15% grape marc with a source of nitrogen (Economides et al., 1980). In Greece, sheep fed diets containing up to 40% grape marc for 10 days showed decreased protein digestibility when grape marc was included at 20% and above (Fegeros et al., 1987). In Iran, feeding male lambs on diets containing up to 10% dried grape pomace (juice production) improved growth performance as well as the triglyceride level. Dietary level of 15% and above was detrimental to growth and feed efficiency (Bahrami et al., 2010a; Bahrami et al., 2010b). In Spain, feeding lambs with a low amount (5%) of dried grape marc (red grape) did not affect intake, average daily gain, carcass yield and carcass characteristics (Guerra-Rivas et al., 2013b). In Romania, feeding above 125 g/d of dried grape pomace was detrimental to growth (Nistor et al., 2014). A study in China was more positive: dietary supplementation of lamb diets with 8-16% of grape pomace had a positive effect on feed conversion efficiency, average daily body weight gain, carcass characteristics and nutrient utilization (Lu ZhenZhen et al., 2015).

Ewes

In Greece, grape marc included at 19% in the diets of dairy ewes increased PUFA concentration in the milk as well as the concentration of cis-9, trans-11 CLA and vaccenic acid (C18:1 trans-11) (Tsiplakou et al., 2008). However, a study in Spain with ewes fed 5 or 10% red grape wine pomace (combined with 2.7% linseed oil) concluded that grape pomace did not affect the percentages of total saturated, monounsaturated, and polyunsaturated fatty acids (Manso et al., 2016).

The effect of grape pomace in ewes' diet on their lambs was investigated in Spain. Feeding lactating ewes with 5 or 10% of red grape wine pomace resulted in lambs having higher levels of vaccenic acid, rumenic acid (C18:2 cis-9 trans-11) and a higher n3/n6 ratio in the intramuscular fat, though the PUFA and saturated fatty acids were not affected. The lipid oxidation during storage was lower for the meat of lambs whose mothers were fed grape pomace (Guerra-Rivas et al., 2015a; Guerra-Rivas et al., 2015b).

Goats

In Greece, grape marc included at 19% in the diets of dairy goats had little or no effect on the fatty acid profile of milk (Tsiplakou et al., 2008)

Pigs 

Grape pomace has a poor nutritive value for pigs due to its high fibre and high tannin content and there indeed is scarce information about its use as a main source of nutrients in pig feeding. In Australia, dried winery pomace included in pig diets decreased feed efficiency when fed 15% and above, and decreased weight gain when fed 20% and above (Farrel et al., 1983). In France, destemmed grape pomace could be included in pig diets up to 20% (Février et al., 2009).

Since the 2000s, grape pomace added in limited amounts (5% or less) has been investigated as a source of beneficial proanthocyanidins and flavonoids and of favourable fatty acids. Feeding piglets a diet containing 3.5% (DM basis) red grape pomace increased the number of colonic bacteria (Streptococci, Enterococci, Lactobacilli) and positively influenced the white blood cell mRNA gene expression marker of immunological marker genes (Sehm et al., 2011). In Korea, feeding finishing pigs with a diet containing 3% of dried grape pomace fermented with Saccharomyces boulardii had a positive effect on average daily gain, DM and N digestibility, altered the fatty acid profile of the subcutaneous fat (reduced saturated fatty acids and increased PUFA) and meat quality attributes (marbling score, redness and yellowness values, anti-oxidative ability) (Yan et al., 2011). In Romania, the addition of 5% dried grape pomace in the diet of growing pigs increased the concentration of n-3 fatty acids (particularly alpha-linolenic acid) in the longissimus dorsi muscle (Habeanu et al., 2015).

Poultry 

Grape pomace has a poor nutritive value for poultry due to its high fibre and high tannin content and there is scarce information about its use as a main source of nutrients in poultry feeding. Most of the work done since the 2000s concerns the use of grape pomace for its potential benefits on health and product quality.

Broilers

In Australia, dried winery pomace included in broiler diets decreased feed efficiency when fed 12% and above, and decreased weight gain when fed 18% and above (Farrel et al., 1983). Later studies have tested much smaller amounts of grape pomace, usually between 1 to 6%. Several studies in Spain have looked at the effects of grape pomace or grape pomace concentrate on broiler meat quality and gut flora and morphology (Chamorro et al., 2015). Grape pomace added at 0.5 to 3% dietary level to broiler diets reduced the lipid oxidation of meat during refrigerated storage and increased liver α-tocopherol concentration (Goñi et al., 2007). A grape pomace concentrate (containing 15% condensed tannins) included up to 6% in broiler diets did not impair chicken growth performance, digestive organ sizes, and protein digestibility, and increased antioxidant activity in diet, excreta, ileal content, and breast muscle. It was equally as effective in antioxidant potential as vitamin E. In a later experiment, a diet including 6% of the same grape pomace concentrate increased the biodiversity of intestinal bacteria and modified gut morphology in a way potentially favourable to nutrient absorption (Brenes et al., 2008; Viveros et al., 2011). In Iran, red grape pomace (juice production) included in broiler diets decreased broiler performance linearly when added at more than 2%, but it also increased blood glucose level and plasma antioxidants (Khodayari et al., 2014). In Romania, grape pomace included at 2% in broiler diets had a slight positive effect on performance (Pop et al., 2015).

Laying hens

In the United States, feeding grape pomace has been tested successfully to induce molting before the second laying phase (McKeen, 1984). In Turkey, the addition of up to 6% grape pomace to laying hen diets did not significantly affect performance, egg quality and serum total cholesterol, total protein and triglyceride levels, and it reduced egg yolk malondialdehyde (MDA), which may improve egg shelf life (Kara et al., 2016).

Horses and donkeys 

Grape marc has been used for horses in proportions of up to 10% of the ration (Göhl, 1982).

Nutritional tables
Tables of chemical composition and nutritional value 

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

All types included: with or without stems, with or without seeds, from wineries, distillation or juice production

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 91.8 2.5 85.9 97.8 430  
Crude protein % DM 13.7 1.0 11.1 16.3 395  
Crude fibre % DM 26.1 3.5 17.6 35.4 437  
NDF % DM 64.1 4.3 50.7 74.6 203  
ADF % DM 54.7 4.9 42.6 67.0 208  
Lignin % DM 33.4 5.6 19.9 46.2 276  
Ether extract % DM 6.1 1.1 3.6 9.1 161  
Ash % DM 7.8 2.3 2.4 13.8 292  
Starch (polarimetry) % DM 0.6       1  
Total sugars % DM 0.8 0.4 0.0 2.1 73  
Gross energy MJ/kg DM 19.1 1.6 17.6 21.7 6 *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 9.0 3.1 4.1 17.9 105  
Phosphorus g/kg DM 2.6 0.5 1.4 4.0 107  
Potassium g/kg DM 12.0 3.7 7.2 21.7 69  
Sodium g/kg DM 0.2 0.1 0.0 0.4 30  
Magnesium g/kg DM 0.8 0.1 0.7 1.0 5  
Manganese mg/kg DM 13 6 5 18 4  
Zinc mg/kg DM 26 14 11 43 4  
Copper mg/kg DM 70 41 0 162 137  
Iron mg/kg DM 266 140 160 425 3  
               
Amino acids Unit Avg SD Min Max Nb  
Alanine % protein 4.6   4.3 4.9 2  
Arginine % protein 3.2       1  
Aspartic acid % protein 5.9   4.7 7.0 2  
Cystine % protein 1.3       1  
Glutamic acid % protein 13.2   11.4 15.1 2  
Glycine % protein 5.5   5.4 5.5 2  
Histidine % protein 2.3   1.8 2.8 2  
Isoleucine % protein 3.9   3.9 4.0 2  
Leucine % protein 6.8   6.7 6.8 2  
Lysine % protein 4.6   3.9 5.4 2  
Phenylalanine % protein 4.0       1  
Proline % protein 4.7       1  
Serine % protein 3.4       1  
Threonine % protein 3.8   3.5 4.1 2  
Tyrosine % protein 2.4   2.0 2.8 2  
Valine % protein 3.6   2.4 4.7 2  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins (eq. tannic acid) g/kg DM 135.7 92.5 15.4 343.0 15  
Tannins, condensed (eq. catechin) g/kg DM 92.1 53.0 20.4 138.1 4  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 30.1 5.4 22.5 37.2 7  
Energy digestibility, ruminants % 28.0         *
DE ruminants MJ/kg DM 5.3         *
ME ruminants MJ/kg DM 4.3         *
Nitrogen digestibility, ruminants % 48.0 11.4 8.6 48.0 4 *
a (N) % 10.0   4.4 15.7 2  
b (N) % 14.5   11.6 17.5 2  
c (N) h-1 0.041   0.025 0.057 2  
Nitrogen degradability (effective, k=4%) % 17         *
Nitrogen degradability (effective, k=6%) % 16 9 9 32 6 *
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, rabbit % 25.5         *
DE rabbit MJ/kg DM 4.9   3.9 5.8 2  
Nitrogen digestibility, rabbit % -3.3   -13.0 6.4 2  
MEn rabbit MJ/kg DM 4.9         *

The asterisk * indicates that the average value was obtained by an equation.

References

AFZ, 2011; Alibes et al., 1990; Bahrami et al., 2010; Bruttini, 1923; Chapoutot et al., 1990; Fegeros et al., 1987; Fernandez Carmona et al., 1996; Fraga et al., 1991; Goñi et al., 2007; Guemour et al., 2010; Hadjipanayiotou et al., 1976; Kandylis et al., 1986; Krishna, 1985; Maertens et al., 2001; Moate et al., 2014; Mollaei et al., 2015; Morgan et al., 1980; Parigi-Bini et al., 1980; Regadas Filho et al., 2011; Sarcicek et al., 2002; Tsiplakou et al., 2008; Winkler et al., 2015; Wolter et al., 1979; Zalikarenab et al., 2007

Last updated on 21/10/2016 13:23:31

All types included: with or without stems, with or without seeds, from wineries, distillation or juice production

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 38.7 7.5 27.3 59.5 21  
Crude protein % DM 11.6 2.1 8.3 15.5 21  
Crude fibre % DM 25.1 4.6 15.8 32.5 19  
NDF % DM 50.7 13.1 30.6 74.2 9  
ADF % DM 42.8 12.5 25.7 59.4 8  
Lignin % DM 30.7 8.8 20.2 38.8 4  
Ether extract % DM 5.2 2.0 2.7 9.9 16  
Ash % DM 7.3 2.7 3.2 12.8 22  
Total sugars % DM 18.5 11.5 3.9 31.8 7  
Gross energy MJ/kg DM 18.8 1.5 17.6 20.8 4 *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 9.0 3.9 4.7 16.3 6  
Phosphorus g/kg DM 2.7 0.5 2.0 3.3 6  
Copper mg/kg DM 78       1  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins (eq. tannic acid) g/kg DM 35.4 8.4 28.0 45.0 4  
Tannins, condensed (eq. catechin) g/kg DM 74.9 76.7 21.0 202.6 5  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 32.5 9.2 14.0 56.0 12  
Energy digestibility, ruminants % 29.9   29.9 48.7 2 *
DE ruminants MJ/kg DM 5.6   5.6 9.1 2 *
ME ruminants MJ/kg DM 4.6         *
Nitrogen digestibility, ruminants % 15.2 9.3 5.5 30.0 6  
a (N) % 22.5 15.7 4.4 33.0 3  
b (N) % 22.4 12.9 14.0 37.2 3  
c (N) h-1 0.034 0.013 0.020 0.045 3  
Nitrogen degradability (effective, k=4%) % 33 13 17 40 3 *
Nitrogen degradability (effective, k=6%) % 31 14 14 39 3 *

The asterisk * indicates that the average value was obtained by an equation.

References

Abarghuei et al., 2015; AFZ, 2011; Alibes et al., 1990; Basalan et al., 2011; Baumgärtel et al., 2007; Maymone et al., 1945; Molina-Alcaide et al., 2008; Oluyemi et al., 1982; Tisserand et al., 1989; Vargas et al., 1965; Winkler et al., 2015

Last updated on 21/10/2016 13:24:52

All types included: with or without stems, with or without seeds, from wineries, distillation or juice production

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 38.7 7.5 27.3 59.5 21  
Crude protein % DM 11.6 2.1 8.3 15.5 21  
Crude fibre % DM 25.1 4.6 15.8 32.5 19  
NDF % DM 50.7 13.1 30.6 74.2 9  
ADF % DM 42.8 12.5 25.7 59.4 8  
Lignin % DM 30.7 8.8 20.2 38.8 4  
Ether extract % DM 5.2 2.0 2.7 9.9 16  
Ash % DM 7.3 2.7 3.2 12.8 22  
Total sugars % DM 18.5 11.5 3.9 31.8 7  
Gross energy MJ/kg DM 18.8 1.5 17.6 20.8 4 *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 9.0 3.9 4.7 16.3 6  
Phosphorus g/kg DM 2.7 0.5 2.0 3.3 6  
Copper mg/kg DM 78       1  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins (eq. tannic acid) g/kg DM 35.4 8.4 28.0 45.0 4  
Tannins, condensed (eq. catechin) g/kg DM 74.9 76.7 21.0 202.6 5  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 32.5 9.2 14.0 56.0 12  
Energy digestibility, ruminants % 29.9   29.9 48.7 2 *
DE ruminants MJ/kg DM 5.6   5.6 9.1 2 *
ME ruminants MJ/kg DM 4.6         *
Nitrogen digestibility, ruminants % 15.2 9.3 5.5 30.0 6  
a (N) % 22.5 15.7 4.4 33.0 3  
b (N) % 22.4 12.9 14.0 37.2 3  
c (N) h-1 0.034 0.013 0.020 0.045 3  
Nitrogen degradability (effective, k=4%) % 33 13 17 40 3 *
Nitrogen degradability (effective, k=6%) % 31 14 14 39 3 *

The asterisk * indicates that the average value was obtained by an equation.

References

Abarghuei et al., 2015; AFZ, 2011; Alibes et al., 1990; Basalan et al., 2011; Baumgärtel et al., 2007; Maymone et al., 1945; Molina-Alcaide et al., 2008; Oluyemi et al., 1982; Tisserand et al., 1989; Vargas et al., 1965; Winkler et al., 2015

Last updated on 21/10/2016 13:24:52

All types included: with or without stems, with or without seeds, from wineries, distillation or juice production

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 37.0 7.6 29.5 47.1 5  
Crude protein % DM 12.9 1.1 10.9 14.2 7  
Crude fibre % DM 27.7 2.6 24.2 29.9 6  
NDF % DM 54.2 14.4 40.1 68.9 3  
ADF % DM 53.3 8.7 44.8 62.1 3  
Lignin % DM 36.2   30.1 42.2 2  
Ether extract % DM 6.8 4.3 2.0 12.6 5  
Ash % DM 7.1 1.3 5.6 8.8 6  
Starch (polarimetry) % DM 0.3       1  
Gross energy MJ/kg DM 19.4         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 6.1       1  
Potassium g/kg DM 19.4       1  
Sodium g/kg DM 0.2       1  
Magnesium g/kg DM 1.2       1  
Copper mg/kg DM 34       1  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins (eq. tannic acid) g/kg DM 36.0       1  
Tannins, condensed (eq. catechin) g/kg DM 8.1       1  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 25.5 7.0 14.0 32.5 5  
Energy digestibility, ruminants % 23.4         *
DE ruminants MJ/kg DM 4.5         *
ME ruminants MJ/kg DM 3.7         *
Nitrogen digestibility, ruminants % 42.1 7.4 2.0 42.1 4 *

The asterisk * indicates that the average value was obtained by an equation.

References

Alibes et al., 1990; Larwence et al., 1983; Moate et al., 2014; Reyne et al., 1977; Winkler et al., 2015

Last updated on 21/10/2016 13:26:47

References
References 
Datasheet citation 

Heuzé V., Tran G., 2016. Grape pomace. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/691 Last updated on October 24, 2016, 23:32